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· 02 Nov 2022

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How to Calculate Rigid PCBA Trace Current

When designers are designing Rigid PCBAs, hint layout is certainly considered one among their key tasks. Designers can without difficulty calculate the present day wearing potential of the Rigid PCBA board via the PCBA hint present day calculator. The cause why Rigid PCBA strains are of precise situation is that it immediately influences the present day potential. The IPC-2221 General Design Guidelines are a very good start line for without difficulty measuring the width of board conductors or “strains” with a programmed formula. Of course, its energy isn't always most effective to this, it is usually greater effective features, such as: the period of the hint, the entire resistance cost of the circuit board, the energy loss as a result of the hint resistance. Note : The Trace Calculator is an effective layout tool, however its consequences aren't genuine and want to be adjusted in step with the real software of the project. In the subsequent content, FS Technology will recognition at the creation of hint calculation formulation and symbols.

Calculation method of Rigid PCBA maximum current
The minimal width and thickness of conductors at the completed FS Technology Rigid PCBA board want to be decided consistent with the present day sporting capability required with the aid of using the venture and the most allowable conductor temperature rise. For conductors on outer and internal layers of revealed boards, minimal conductor width and thickness. As proven below:

External conductor

Conductor Trace Width vs. Cross SectionInternal conductor

We can calculate the size of the cross-sectional area according to the formula provided by FS Technology

A = (I / (k * T RISE b )) 1/c
The formula for calculating the maximum current that a trace can carry is as follows:

W = A / (T * 1.378 [mils/oz/ft 2 ])

Explain :

A : Refers to the size of the cross-sectional area, the unit is mils²

T : Refers to the thickness of the FS Technology Rigid PCBA trace, the unit is oz/ft²
W : Refers to the trace width, the unit is mils
IMAX : Refers to the maximum current that the trace runs through, the unit is A

T RISE : Refers to the maximum desired temperature rise, the unit is °C

K, B, C : Refer to constant values. According to IPC-2221A standard, 6.2 (“Requirements for Conductive Materials”), their inner layer values are as follows : K = 0.048 B = 0.44 C = 0.725

How to Calculate Tracking Temperature
The formula for calculating the total trace temperature of the circuit board is as follows:

TTEMP = TRISE + TAMB

Explain :

T TEMP : Refers to the temperature of the trace, the unit is °C

T RISE : Refers to the maximum desired temperature rise, the unit is °C
T AMB : Refers to the ambient temperature, the unit is °C
We outline the allowable temperature upward push of the conductor because the distinction among the important cost of the secure working temperature of the FS Technology Rigid PCBA laminate and the most temperature that the Rigid PCBA can withstand. For convection cooled PCBA assemblies, the thermal surroundings is the most ambient temperature at which the broadcast board may be used. For conduction-cooled PCBA assemblies in a convection surroundings, the temperature upward push is because of the strength dissipated through the conduction-cooled additives, and the temperature upward push via the broadcast board and/or warmth sink to the bloodless plate need to additionally be considered. For conduction cooled FS Technology Rigid PCBA assemblies in a vacuum surroundings, the thermal surroundings is the temperature upward push because of the dissipated strength of the additives and the temperature upward push via the FS Technology PCBA and/or warmth sink to the bloodless plate.

How to Calculate Resistance
Convert the cross-sectional area from mils² to cm² before doing the calculation:

A’ = A * 2.54 * 2.54 * 10-6

Begin to calculate the resistance, the formula for the resistance calculation is as follows:

R = (ρ * L / A’) * (1 + α * (TTEMP – 25 °C))
Explain :

T : Refers to the thickness of the trace, the unit is mils²

W : Refers to the trace width, the unit is mils
R : Refers to the resistance value, the unit is Ω

ρ : Refers to the resistivity parameter, the resistivity parameter of copper is 1.7E-6 [Ω·cm]
L : Refers to the trace length, the unit is cm
α : Refers to the temperature coefficient of resistivity, copper has a temperature coefficient of resistivity of 3.9E-3 [1/°C]
T TEMP : Refers to the trace temperature, the unit is °C
How to Calculate Voltage Drop
The formula for calculating the voltage drop is as follows :

VDROP = I * R

Explain :

V DROP : Refers to the voltage drop, the unit is V

How to Calculate Power Consumption
The formula for calculating FS Technology Rigid PCBA power consumption is as follows:

PLOSS = R * I2

Explain :

P LOSS : Refers to power loss, the unit is W

Example 1

Inputs W = 12 mil T = 5 mil TRISE = 30 °C TAMB = 25 °C L = 12 inch

Output Cross-section Area = 60.00 mils2 IMAX = 4.17 A

Additional output Trace Temperature = 55 °C Resistance = 0.150 Ω Voltage Drop = 0.626 V Power Dissipation = 2.608 W

Example 2

Inputs W = 10 mil T = 3 oz/ft2 TRISE = 20 °C TAMB = 18 °C L = 25 cm

Output Cross-section Area = 41.34 mils2 IMAX = 2.66 A

Additional output Trace Temperature = 38 °C Resistance = 0.167 Ω Voltage Drop = 0.444 V Power Dissipation = 1.182 Whttps://www.fs-pcba.com/